Differences in printmodes typically involve a tradeoff between image quality (IQ) and print speed. While printmodes that improve both image quality and speed are desirable, most printmode designs merely attempt to find the appropriate balance between image quality and print speed that is best suited to a particular printing application. For example, image quality is typically more important for photo printing applications, while printing speed may be more important for simple text printing applications. In a scanning-type inkjet printer where a printhead scans back and forth across the media on a carriage), a unidirectional printmode is often used when printing photos, since this printmode provides high image quality. However, the higher image quality of the unidirectional printmode comes at the expense of print speed, because lines of the image are printed in only one direction (usually from left to right across the media). In bidirectional printmodes, one line is typically printed from left to right, followed by a line being printed from right to left, and so on. Bidirectional printing is faster than printing in one direction only, because there is no need to wait for the printhead carriage or other imaging mechanism to return to the left margin before starting a new line.
Throughout the drawings, identical reference numbers designate similar, but not necessarily identical, elements.